Control mechanisms for steam driven diaphragm valve sound transmitters

ABSTRACT

A control mechanism for a steam driven sound transmitter of the type having a valve diaphragm which during signalling oscillates relative to a seat and periodically opens and closes the communication for the steam between an inlet chamber and an outlet passage opening into a resonance horn but which, when no signal is to be generated, is blocked against the seat by the action of the steam pressure in a back pressure chamber located behind the diaphragm, comprises a valve housing with a cavity, steam passages connecting the inlet chamber and the back pressure chamber with said cavity, a drain passage connecting said cavity with a drainage tank, and a valve-controlled relief passage connecting said cavity with the atmosphere, said passage between the inlet chamber and said cavity having a minimum crosssectional area which is smaller than the minimum cross-sectional area of the relief passage but greater than the minimum crosssectional area of the drain passage.

United States Patet [191 Dahlquist 51 Feb. 12, 1974 CONTROL MECHANISMS FOR STEAM DRIVEN DIAPHRAGM VALVE SOUND TRANSMITTERS [75] Inventor: Nils Axel Viktor Dahlquist, Malmo,

Sweden Kockums Mekaniska Verkstads AB, Malmo, Sweden [22] Filed: Sept. 26, 1972 [21] Appl. No.: 292,372

[73] Assignee:

[58] Field of Search. l16/l42, 59, 142 PP, 142 FV, 116/112, 137, 140; 340/388 Primary Examiner-Louis J. Capozi Attorney, Agent, 0r-FirmBrowne, Beveridge, De

Grandi & Kline [5 7'] ABSTRACT A control mechanism for a steam driven sound transmitter of the type having a valve diaphragm which during signalling oscillates relative to a seat and periodically opens and closes the communication for the steam between an inlet chamber and an outlet passage opening into a resonance horn but which, when no signal is to be generated, is blocked against the seat by the action of the steam pressure in a back pressure chamber located behind the diaphragm, comprises a valve housing with a cavity, steam passages connecting the inlet chamber and the back pressure chamber with said cavity, a drain passage connecting said cavity with a drainage tank, and a valve-controlled relief passage connecting said cavity with the atmosphere, said passage between the inlet chamber and said cavity having a minimum cross-sectional area which is smaller than the minimum cross-sectional area of the relief passage but greater than the minimum cross-sectional area of the drain passage.

2 Claims, 3 Drawing Figures [56] References Cited UNITED STATES PATENTS 3,581,705 6/1971 Holm ll6/l42 FF 1 CONTROL MECHANISMS FOR STEAM DRIVEN DIAPHRAGM VALVE SOUND TRANSMITTERS This invention relates to a control mechanism for steam driven diaphragm valve sound transmitters having a diaphragm which during signalling oscillates relative to a seat and periodically opens and closes the communication for the steam between an inlet chamber and an outlet passage opening into a resonance horn but which, when no signal is to be generated, is blocked against the seat under the action of the pressure of the steam in a back pressure chamber located behind the diaphragm, the inlet chamber and the back pressure chamber being connected via passages in a valve housing to a cavity formed in said valve housing and communicating via a drain passage with a drainage tank and via a valve-controlled relief passage with the atmosphere.

A prior art control mechanism for steam driven diaphragm valve sound transmitters of the above mentioned type is described in Swedish Pat. No. 320,611 according to which a valve member movable within the cavity of the valve housing is adapted in signalling position to block the communication between the inlet chamber, the back pressure chamber and the drain passage, but to open the communication between the back pressure chamber and the relief passage and is adapted in non-signalling position to block the relief passage, but to open the communication between the inlet chamber, the back pressure chamber and the drain passage. in the embodiment described, the valve member is a slide which is axially movable within a bore in the valve housing and which produces the said function by operation between two blocking positions in the valve housing. A disadvantage of this mechanism is its sensitivity to impurities. Thus, it has been found that already small amounts of impurities, such as dust particles, may result in a break-down because the axial movement of the slide is hampered or even prevented.

The present invention has for its object to provide a control mechanism for diaphragm valve sound transmitters of the type referred to in the introduction, in which the above-mentioned disadvantage of the prior art control mechanism has been eliminated, thus providing for considerably improved operational reliability, simultaneously as its less complicated construction reduces production costs. Moreover, the present invention aims at providing an improved continuous drainage of the diaphragm valve sound transmitter and at reducing the power requirements of the means for controlling the signalling by means of the sound transmitter.

The above and further objects are substantially realized by a construction in accordance with the characteristic features defined in the appended claim. The invention is more fully described in the following with reference to a preferred embodiment illustrated in the accompanying drawings in which:

FIG. 1 is a longitudinal section through a diaphragm valve sound transmitter having a control mechanism in accordance with the invention;

FIG. 2 is a section on line AA in FIG. 1, with the control valve set in blocked position;

FIG. 3 is a section on line B-B in FIG. 2.

The diaphragm valve sound transmitter illustrated in the drawings comprises a diaphragm housing 1 which consists of a body member 2 and a cover 3 secured thereto. The body member 2 is formed in conventional manner with a hollow mushroom seat 4, the interior of which merges into an outlet passage 5 extending through a resonance horn 6 attached to the body member. A diaphragm 7 is clamped in the diaphragm housing by means of the cover 3, whereby it is held in resilient engagement with the seat 4. The housing has an inlet chamber 8 to which is connected a steam supply line 9. The inside of the cover 3 defines together with the diaphragm 7 a space 10 which usually is termed back pressure chamber. The back pressure chamber 10 communicates with the inlet chamber 8 through passages 11 (FIG. 1) and 12 (FIG. 3) formed in the diaphragm housing and passages l5, 19, 23 formed in the operating valve 13, all in order that when no signal is to be generated, the diaphragm 7 be blocked against the seat 4 under the action of the pressure prevailing in the back pressure chamber.

The operating valve 13 comprises a valve housing 14 which is mounted at the lower edge of the cover 3 by means of screws. The cavity within the valve housing is constituted by an axial bore 15 which at its left-hand end (in FIG. 1) is closed by means of a threaded plug 18. The bore 15 is in communication with the inlet chamber 8 through a passage 19 formed in the valve housing 14 and through the passages 12 formed in the diaphragm housing. Moreover, a radial drain passage 21 is provided in the lower part of the valve housing 14 and extends from the bore 15 through the housing. The drain passage 21 is connected by means of a pipeline 22 to a drainage tank (not shown) which may be the feed-water tank of the steam generator. According to the invention, the drain passage 21 has a minimum cross-sectional area that is smaller than the smallest cross-sectional area of the passages 19 and 12 between the inlet chamber and the bore 15. Moreover, a passage 23 connects the back pressure chamber 10 to the bore 15, whereby the previously mentioned communication between the back pressure chamber 10 and the inlet chamber 8 is established. At its right-hand end (in FIG. 1) the bore 15 opens into a turned cavity at the other end of the valve housing 14, said cavity having a diameter larger than that of the bore 15 and accommodating a guide 24 screwed thereinto. An operating rod 25 is axially movable within said guide 24 which, together with said operating rod 25 and associated details, constitutes a transfer mechanism for transferring the operating movement from a preferably electromagnetical operating member 29 for operating the signalling by means of the sound transmitter. An annular seat 26 of an elastic material resistant to steam is fixed between the inner end of the guide 24 and the bottom of the turned cavity. The opening in the seat 26 forms, together with a passage 27 within the guide and a passage 28 within the diaphragm housing, a relief passage communicating with the atmosphere. According to the invention, the minimum cross-sectional area of the relief passage thus formed is to be greater than the minimum cross-sectional area of the passage 19, 12 between the inlet chamber and the bore 15. The relief passage is closed by means of a valve mechanism which in the illustrated embodiment is constituted by a ball 20, preferably of stainless steel. The ball 20 is provided within the bore 15 for sealing against the annular seat 26 against which it is held by a spring 17.

1n the blocking position, illustrated in FIG. 2, of the control mechanism, the operating rod 25 extends up to the seat 26 with the rod end in immediate proximity to the ball 20. The operating rod 25 projects in the opposite direction some distance beyond the guide for axial actuation of the operating member 29. The sound transmitter as well as the operating means and the pipe connections are mounted in a common frame generally designated 30 in FIG. 2.

The control mechanism functions in the following manner:

In blocking position, that is when no signal is to be generated, the movable parts of the control mechanism occupy the position shown in FIG. 2. The ball 20 is thereby urged into sealing engagement with the seat 26, the communication of the relief passage with the atmosphere being interrupted. Simultaneously, the inlet chamber 8, the back pressure chamber and the drain passage 21 are in communication with each other through the passages 12 formed in the diaphragm housing, the passage 19 and the bore 15 in the valve housing, as well as the passage 23 in the valve housing and the passage 11 in the diaphragm housing. The same steam pressure will thus prevail in the inlet chamber 8 and in the back pressure chamber 10, causing the diaphragm 7 to be urged towards the seat 4 for sealing engagement therewith. The diaphragm housing is kept heated because the inlet chamber 8 and the back pressure chamber 10 in the diaphragm housing are completely filled with steam, also when no signal is generated. At the same time, the condensation water forming within the inlet chamber 8 and in the back pressure chamber 10 escapes continuously through the passages 12, 19 and 11, 23, the bore 15 and the drain passage 21 to the drainage tank. As the pressure prevailing in the drainage tank corresponds to the ambient pressure, also a given amount of steam will escape continuously from the inlet chamber 8 through the passages 11 and 19. However, because the drain passage 21 has a minimum cross-sectional area that is smaller than the crosssectional area of the communication passages 11, 19 between the inlet chamber 8 and the bore 15, the back pressure in the back pressure chamber will be built up and maintained. By reason of the continuous discharge of condensation water and a minor quantity of steam, the sound transmitter is always kept in condition for faultless signalling.

When a signal is to be generated, the operating member 29 is enabled so that it urges the operating rod 25 towards the seat 26. The ball is then moved away from the seat, whereby communication is established with the atmosphere through the relief passage which comprises the opening of the seat 26 and the passages 27 and 28. The steam pressure in the back pressure chamber is then relieved in that the steam escapes through the relief passage to atmosphere. Due to the resulting pressure difference between the inlet chamber and the back pressure chamber, the diaphragm 7 is caused to leave the seat 4', whereby signalling is initiated in conventional manner. Because the minimum cross-sectional area of the relief passage is greater than the minimum cross-sectional area of the passages 12 and 19 between the inlet chamber 8 and the bore 15, rapid relief of the pressure in the back pressure chamber 10 is possible, despite a certain leakage of steam from the inlet chamber to the bore 15. The expression minimum cross-sectional area" in connection with different passages in the control mechanism naturally implies the minimum effective cross-sectional area which, for instance in connection with the relief passage, can imply the minimum cross-sectional area of the seat opening 26 minus the cross-sectional area of the operating rod 25 actuating the ball 20. As already mentioned, the relief passage is in direct communication with the atmosphere, but it will be obvious that a back pressure regulator of the type described in Swedish Pat. No. 320,61 1 can be connected to the relief pas sage. However, trails made with a control mechanism according to the present invention have shown that it is possible to omit the back pressure regulator and to let the relief passage open directly to the ambient atmosphere. In the control mechanism according to Swedish Pat. No. 320,61 1, the drain passage was connected to the drainage tank via a condensation water separator. This necessitated blocking the inlet chamber, the back pressure chamber and the drain passage from one another to avoid the risk of any condensation water in the drain passage being sucked back into the inlet chamber where a certain pressure reduction is obtained during signalling. In the mechanism of the present invention, the drain passage has been connected directly to the drainage tank in which atmospheric pressure prevails. In view hereof, no counterpressure can be built up within the drain passage, and the risk of condensation water being sucked from the drain passage into the inlet chamber therefore does not exist. Consequently, no blocking of the inlet chamber, the back pressure chamber and the drain passage is required in the control mechanism of the present invention. In the control mechanism according to Swedish Pat. No. 320,61 1, the said blocking was produced by axially displacing a valve slide within the bore of the valve housing, which necessitated a comparatively large operating stroke of the electromagnetic control member. The control mechanism of the present invention requires a much shorter length of stroke for the operating member 29 since the operating rod 25 merely has to cause the ball 20 to rise but a relatively small distance from the seat 26. As the operating member 29 can be dimensioned for a shorter length of stroke, the production costs of the operating member will be lower, simultaneously as operational advantages are gained because the operating member which preferably is electromagnetic, requires a lower starting current.

The invention is not limited to the preferred embodiment described above but can be modified in several ways within the scope of the appended claim.

What 1 claim and desire to secure by letters patent is:

l. A control mechanism for steam driven diaphragm sound transmitters having a diaphragm which during signaling oscillates relative to a seat and periodically opens and closes the communication for the steam between an inlet chamber and an outlet passage opening into a resonant horn but which, when no signal is to be generated, is blocked against the seat by the action of the pressure of the steam in a back pressure chamber located behind the diaphragm, the inlet chamber and the back pressure chamber being connected via passages in a valve housing to a cavity formed in said valve housing and communicating via a drain passage with a drainage tank and via a valve-controlled relief passage with the atmosphere, wherein the improvement com prises the passage between the inlet chamber and the valve-controlled relief passage comprises an annular passage communicating with a relief passage open to the atmosphere and a' valve mechanism which closes said annular passage to escape of steam to the atmosphere through said annular passage. 

1. A control mechanism for steam driven diaphragm sound transmitters having a diaphragm which during signaling oscillates relative to a seat and periodically opens and closes the communication for the steam between an inlet chamber and an outlet passage opening into a resonant horn but which, when no signal is to be generated, is blocked against the seat by the action of the pressure of the steam in a back pressure chamber located behind the diaphragm, the inlet chamber and the back pressure chamber being connected via passages in a valve housing to a cavity formed in said valve housing and communicating via a drain passage with a drainage tank and via a valve-controlled relief passage with the atmosphere, wherein the improvement comprises the passage between the inlet chamber and the cavity within the valve member having a minimum cross-sectional area which is smaller than the minimum cross-sectional area of the relief passage, but greater than the minimum cross-sectional area of the drain passage.
 2. The control mechanism of claim 1 wherein the valve-controlled relief passage comprises an annular passage communicating with a relief passage open to the atmosphere and a valve mechanism which closes said annular passage to escape of steam to the atmosphere through said annular passage. 